At present, demanding on gemstone identification is increasing, and as the rapid development of artificial-gemstone technology, the gemstone identification has become increasingly difficult. There are generally five detection methods for gemstone identification, including: 1) identification by macroscopic observation (for example, observing color, shape, luster, cleavage, etc.); 2) identification by physical property testing (for example, testing relative density, refractive index, hardness, etc.); 3) identification by polarizing microscope based on crystal optical properties; 4) chemical composition analysis (for example, simple chemical analysis, bulk chemical analysis, electron probe microanalysis, etc.); and 5) crystal structure analysis (for example, x-ray diffraction analysis, infrared spectroscopic analysis, electronic probe analysis, Raman spectrometer analysis, gemstone spectroscope analysis, ultraviolet spectrophotometer analysis, etc.). In the testing process of the methods 1), 2) and 3), the analysis results thereof rely heavily on experiences of operators and are affected greatly by subjective factor, and therefore, it is not conducive to form a standard for objectively measuring the authenticity of a gemstone. The method 4) has disadvantages of slow processing speed and often leading to damage the sample, and due to the specificity of gemstone that the gemstone cannot be cut, scratched, broken or eroded arbitrarily, the use of the chemical analysis is limited. In the prior art of gemstone identification, modern analytical instruments as used in the method 5) are more often used for identification, but the gemstone identification devices commonly used in the method 5) have a lot of disadvantages, such as expensive prices thereof, high analysis cost and slow analyzing speed, etc.
The ultraviolet spectrophotometer is most commonly used as a traditional crystal structure analysis instrument, but the ultraviolet spectrophotometer used in measurement is facing the following problems.
1. When an irregular shaped (often called baroque-shaped) gemstone is tested, a incident light may be reflected in any direction from the surface of the gemstone, while the sampling system of the traditional ultraviolet spectrophotometer has a fixed optical path so that it is difficult to ensure a high efficiency collection of reflected light for baroque-shaped samples, and therefore, there is uncertainty in the measurement of baroque-shaped samples.
2. All traditional ultraviolet spectrophotometers use pre splitting, that is, a composite light from a light source would become monochromatic lights after light splitting by a beam splitter and a monochromator, to irradiate to samples, and information would be recorded by an optoelectronic detector. In order to achieve a continuous record of photometric value at different wavelengths, it needs rotation and adjustment of a mechanical device. And it needs to extend the sweep time to ensure the wavelength resolution, resulting in low measurement efficiency. In addition, with the use of a precision mechanical rotating device, there are high demands for debugging and installation of the prior art of the measuring instrument, causing a complex process of the instrument and high cost. Such measurement method is not suitable to the current gemstone identification.